项目实战（1）-拦截器

引入

拦截器的基本作用是：

• 屏蔽链接，防止直接通过链接访问
• 对屏蔽的链接进行使用HandlerInterceptor拦截器处理

关键词

WebMvcConfigurer、InterceptorRegistry、HandlerInterceptor
preHandle、postHandle、afterCompletion

什么是拦截器

拦截器，首先实现拦截：

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Autowired
    LoginTicketInterceptor loginTicketInterceptor;//要注册的拦截器

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //注册拦截器、排除、添加
        registry.addInterceptor(loginTicketInterceptor)
                .excludePathPatterns("/**/*.css", "/**/*.js", "/**/*.png", "/**/*.jpg", "/**/*.jpeg")
                .addPathPatterns("/register", "/login");
    }
}

拦截器，其次是拦截之后干嘛

@Component
public class LoginTicketInterceptor implements HandlerInterceptor {

    private static final Logger logger= LoggerFactory.getLogger(AlphaInterceptor.class);

    //调用前拦截
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
	...//业务逻辑,以登录为例
	//调用方法前，判断/查找登陆凭证，将用户存储到hostHolder中。
        logger.debug("preHandle:"+handler.toString());
        return true;
    }

    //Controller之后，return返回html之前执行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
	...//业务逻辑
	//用户已登录，就同时向前端返回当前登录用户，前端就可以根据用户是否已登陆，进行相应的判断，显示对应的功能
        logger.debug("postHandle:"+handler.toString());
    }

    //返回html之后之执行
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
	...//业务逻辑
	//调用结束，清除用户信息
        logger.debug("afterCompletion:"+handler.toString());
    }
}